/*
 * LensKit, an open-source toolkit for recommender systems.
 * Copyright 2014-2017 LensKit contributors (see CONTRIBUTORS.md)
 * Copyright 2010-2014 Regents of the University of Minnesota
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
package org.lenskit.pf;

import java.util.EnumSet;
import java.util.Set;
import java.util.function.BiConsumer;
import java.util.function.BinaryOperator;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.stream.Collector;


class PMFModelCollector implements Collector<PMFModel.ModelEntry, PMFModel, PMFModel> {
    @Override
    public Supplier<PMFModel> supplier() {
        return PMFModel::new;
    }

    @Override
    public BiConsumer<PMFModel, PMFModel.ModelEntry> accumulator() {
        return (PMFModel::addEntry);
    }

    @Override
    public BinaryOperator<PMFModel> combiner() {
        return (PMFModel::addAll);
    }

    @Override
    public Function<PMFModel, PMFModel> finisher() {
        return Function.identity();
    }

    @Override
    public Set<Characteristics> characteristics() {
        return EnumSet.of(Characteristics.UNORDERED, Characteristics.IDENTITY_FINISH);
    }
}
